In recent decades, the development of archaeobotany in the Mediterranean has made it possible to document the main plant resources exploited, the agricultural practices implemented, as well as major phenomena of circulation and integration of new plant resources within historical societies. Concern-ing the medieval Western Mediterranean world, archaeobotanical studies have recently received a new impulse, allowing for a better characterization of Muslim agriculture, of its diffusion and of its effec-tive implantation in the Iberian Peninsula, both in rural and urban contexts. This innovative work lays the foundations for a new reflection on the persistence and evolution of plant resources production and management in the face of the great political, social and economic changes occurring in this area during the Christian (Re)conquest.The main goal of this paper is to present the results of new studies carried out in a range of frontier medieval sites in Spain, in connection with the research project "Landscapes of (Re)Conquest: Dy-namics of Multicultural Frontiers in Medieval South Western Europe", funded by AHRC. The results, based on studies of seeds and archaeological charcoal issued from samples dated from the 10th to the 15th c., make it possible to draw up a list of the main agro-horticultural productions and their evolution in the face of changing socio-economic dynamics. The question of changes in forest management and fuel economy is also raised.